Google tells me a good kitchen should last 10-15 years. Our kitchen is currently 20 years old, but still seems to be absolutely fine. Cupboards still good, worktops still good, oven could probably do with a professional clean but we mostly use air fryer now so not really an issue. Hob still works fine. We replaced the dishwasher a few years ago. Kitchen floor is tiles, they still seem fine. We repainted it after the toddler years.
Its the same for bathrooms. We've had to re-mastic the bath and replaced the toilet seats when they started looking a bit grotty. I think we've replaced shower heads at various times. But everything still seems to do what its supposed to.
So stupid question #1 - if everything is working as it should then does it really need replacing?
Stupid question #2 - if it does then do i just go to a kitchen/bathroom shop and get some quotes
Question #3 - are there any showrooms to particularly avoid?